OTTAWA, June 28 -- The House of Commons voted Tuesday to guarantee full marriage rights to same-sex couples, reaffirming Canada's sharp difference with the United States over the issue of gay rights and promising an alternative destination for American gay men and lesbians to be married.

The legislation, which opponents acknowledge will easily pass the Senate and which has the support of the government, will make Canada only the third country -- after Belgium and the Netherlands -- to give national recognition to gay marriages.

"The big peaceable kingdom on the U.S. border will demonstrate that it is absolutely possible for religious freedom to coexist with the end of discrimination against gay and lesbian people," said Alex Munter, a gay rights advocate who gathered with other supporters at Parliament Hall in Ottawa to watch the vote.

"Many couples already come from America to get married, and thousands of more will come."

American couples have been wed here since lower courts began to legalize same-sex marriages in some provinces in 2003. The marriage in Ottawa this month of a gay American couple from the popular television show "Amazing Race" is the latest high-profile example.

"We are the only jurisdiction in the world that allows marriage without a residency requirement," noted R. Douglas Elliott, a Toronto lawyer and president of the International Lesbian and Gay Law Association. "Equal marriage is going to become Canada's leading export in the next couple of years."

Although marriages legally performed in another country are traditionally accepted in the United States, the question of whether gay marriages will be recognized in states that have banned same-sex unions is likely to be the subject of court battles, gay rights advocates predict.

The Canadian legislation, which passed the Commons 158 to 133, follows a steady march of court decisions that have already ruled gay marriage legal in eight of 10 Canadian provinces and one territory. In December, the Canadian Supreme Court pointed the way to national legislation by ruling that gay marriage conforms to the Charter of Rights and Freedoms, part of the nation's constitution.

But unlike in the United States, where some legislators and President Bush have actively opposed same-sex marriage, the Canadian Parliament acted to establish a uniform national law. Despite opposition from church leaders and politicians in several provinces, the move is supported by a majority of the Canadian public, in what gay rights advocates say has been a relatively swift turnabout of opinion over a period of several years.

"This is absolutely historic," Munter said of the vote in the Commons. "It reaffirms that Canada is an open and inclusive and tolerant country."

Thousands of same-sex couples have wed in provinces where gay marriage has won court approval. Several prominent national political officials are openly gay, and gays are accepted in the Canadian military with full spousal benefits for partners.

Even the opposition's stance would be seen as liberal in much of the United States. The minority Conservative Party proposed that a civil union be approved for gay couples as an alternative to including gays in the definition of a married couple. But the ruling Liberal Party, buttressed by the Supreme Court, argued that anything short of full marriage recognition would provide unequal rights and shortchange the civil liberties of gays.

"Rights are rights. None of us can or should pick and choose whose rights we will defend and whose rights we will ignore," Justice Minister Irwin Cotler argued on the floor Tuesday. "The government must represent the rights of all Canadians equally."

He stressed, however, that the change would apply only to the right of gays to be married and divorced under civil law. Ministers cannot be forced to perform the marriages if they object.

"In no church, no synagogue, no mosque, no temple, no religious house will those who disagree with same-sex unions be compelled to perform them. Period," Prime Minister Paul Martin said in a major address giving government support to the bill in February. "This legislation is about civil marriage, not religious marriage."

But opposition to the bill was emotional. About two dozen Liberal Party members voted against the bill, and a Liberal cabinet member resigned rather than support it.

"This is going to have a direct impact on our society," argued Richard Harris, a Conservative member of Parliament. "It is in direct conflict with the traditional way civilization has grown and the traditional foundations of society."

Opponents of same-sex marriage held prayer vigils across the country Sunday. But in Toronto, tens of thousands, including many prominent political figures, marched in the annual gay pride parade.

The bill they supported ensures that Canada will be a symbolic counterpoint to its southern neighbor. In the United States, 40 states have passed laws or constitutional amendments banning marriages between those of the same sex. Few states, however, have laws specifically banning recognition of marriages approved in other jurisdictions. Diplomatically, legal marriages performed in another country are traditionally honored by the United States.

A gay Canadian couple told reporters in Toronto this week that they were barred from a flight to Atlanta because a U.S. Customs agent at the Toronto airport refused to accept their customs declaration as a married couple. Kevin Bourassa and Joe Varnell said they were going to Georgia for a human rights conference when they were told by a supervisor that the United States did not recognize their 2001 marriage in Ottawa.